Doris Enders: "US letterboxes are great! I love the little flag which indicates that there is something to pick up!"

Liang MingYu: "A broken light and a working light at a post office."

Helena Popovich: "While on a road trip in California, I saw many mailboxes right next to the road. Different shapes and colours." Next week the theme is cycling and the deadline for your entries is 8 May. If you would like to enter, send your pictures to yourpics@bbc.co.uk. Further details and terms can be found by following the link below this gallery.